1. Field of the Invention
The present invention relates to a glucose sensor, and especially relates to an optical waveguide type glucose sensor, a device for optical waveguide type glucose measurement, a system for optical waveguide type glucose measurement and a methodology for optical waveguide type glucose measurement for measuring glucose concentration in a solution such as blood.
2. Description of the Related Art
In the Japanese Patent Laid-Open Publication No. Hei 9 (1997)-61346, for example, a planar optical waveguide type glucose sensor has been disclosed. This glucose sensor has a structure in which a pair of gratings, to/from which a light comes in/goes out, are formed on a surface of a substrate, a ingle optical waveguide layer is formed on a part of the surface of the substrate which is located between the gratings, and a film which has molecular recognition and information transformation function is formed on the optical waveguide layer.
In the glucose sensor made up from such a structure, biomolecules contained in blood and the like are analyzed as follows. The biomolecules contained in blood extracted from an analyte are kept in contact with a film which has molecule recognition and information transformation function. A light such as a laser light is made incident to an optical waveguide layer via a grating. An evanescent wave is generated. A change in the quantity of the evanescent wave due to a reaction of the biomolecules contained in blood and the like on a film provided on the optical waveguide layer is detected by a light detector which receives the light emanating from the grating. Thus, analysis of the biomolecules contained in blood and the like is realized.
However, in the conventional glucose sensor there have been problems, such as, since the optical waveguide layer is made up with a single layer, there is a limit to the sensitivity in detecting the change in the quantity of the evanescent wave generated in the optical waveguide layer, and also the film structure on the optical waveguide layer is not suitable for analysis of the extremely small amounts of biomolecules contained in blood and the like which are extracted from the analyte.
The intention of the present invention is to provide an optical waveguide type glucose sensor which enables highly sensitive and highly accurate analysis of extremely small amounts of glucose contained in a body fluid, for example, extracted from an analyte, a device for optical waveguide type glucose measurement by use of the optical waveguide type glucose sensor, a system for the optical waveguide type glucose measurement and a methodology for the optical waveguide type glucose measurement